Boris knows there is NO answer or solution to the Irish border- none whatsoever. That was clear 2 years ago, and as Javid says, that was at a time when a Deal was in sight- and not now, when No Deal throws much much larger problems.
Watch Javid replying to Yvette Cooper, quite a long time ago And now we are 2 months away, with a possible No Deal- how on earth does Boris think (he doesn't actually, it is all bluster and bluff, and he himself, and the EU, know this full well):
www.facebook.com/FullEnglishBrexit/videos/2190347361034802/